We'd me much better off buying Bernardo to add creativity on the RW than playing a waster at #10, James isn't cheap either, and putting a player like him in means Pogba will be stuck too deep, it's just pissing more money away, and every time we move to a 3 we'd have no place for James because he's too slow and too lazy to operate as a wider player, there is zero need to buy expensive luxuries like him, and Mata's best football for us has come playing off the RW with freedom to roam, he's too weak and slow to play as an actual #10 and gets crowded out or bullied off the ball when he starts there, the RW floating option allows him to use his intelligence and movement to pick up pockets of space and effect the game.
This 4-2-3-1 is a complete waste of the unique talent of Pogba, put him in a 3 with another #8 that can alternate in pushing forward and you get the optimum use of him, not in a system where a lazy #10 like James takes up his space to burst into and create chances. As far as needing depth for the 4-3-3, we can buy another #8 instead of pissing away £60M on James, then along with Pereira coming back we'll have 4 options for the 2 #8 roles. You can't control games when you give up a spot in your midfield to a basic #10 who doesn't work hard.
Bar Porto he's consistently opted for one purely defensive fullback in his team, it's been a feature at Chelsea and Madrid in particular, the need for a tall fullback also really limits the options but I know Jose has his quirks. We could do with one proper wide man in the squad, he needn't be a starter but it's a good option to have as seen by all of the top teams in Europe bar Barca.